Brake hose

Abstract

A brake hose is made by laminating an inner tube rubber layer, lower yarn layer, intermediate rubber layer, upper yarn layer, and cover rubber layer. The rubber material of the inner tube rubber layer and intermediate rubber layer is a blend material in which 40 to 80 wt % is IIR and the remainder is EPDM. The upper yarn is PVA, and the upper yarn is PET, where the tensile strength per unit decitex is at least 6.5 g, and the 2.7 g elongation is 2.6±1%. The brake hose has better water penetration resistance and can be produced by a general purpose method.

Description

[0001] This application claims the benefit of and priority from Japanese Application No. 2005-88347 filed Mar. 25, 2005, the content of which is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The invention relates to a brake hose formed by the lamination of a plurality of rubber layers and reinforcing layer, which is used in automobiles and the like. [0004] 2. Description of the Related Art [0005] A conventional brake hose used in automobiles is described in JP-A-63-303,288 or JP-A-6-305,083 (see FIG. 11). FIG. 11 is a cross section of the main components of a conventional brake hose 100. The brake hose 100 is formed by laminating several layers of rubber and yarn layers because of the need for high pressure resistance against brake hydraulics. That is, the brake hose 100 is formed by laminating an inner tube rubber layer 102 forming a flow path 101 for flowing brake oil, a lower yarn layer 104, an intermediate layer 106, an upp...

AI Technical Summary

Benefits of technology

[0007] An advantage of some aspects of the invention is to provide a brake hose which has better resistance to water penetration and which can be produced by a general purpose method.

[0009] In the brake hose of the invention, the rubber material of the inner tube rubber layer and intermediate rubber layer involves the use of a blend in which 40 to 80 wt % is IIR and the rest is EPDM, so as to prevent the penetration of moisture. The upper yarn involves the use of polyvinyl alcohol (PVA) so that the penetration of water into the interior layers can be controlled because of the high water retention of the material. Furthermore, the lower yarn layer is PET, allowing high durability and low volume expansion to be combined. The brake hose can thus reduce the amount of water penetrating from the outside into the interior, while preserving durability and low volume expansion, and can better prevent the phenomenon of vapor locks.

[0010] In addition, the inner tube rubber layer and intermediate rubber layer can e made of single layers by the extrusion of blended materials, and are thus easier to produce than in conventional techniques.

[0011] In a preferred embodiment of the invention, the upper yarn layer is formed by intertwining two groups of upper yarn formed from single yarn bundles, the two groups of upper yarn being interwoven at a braiding angle of 57 to 61 degrees. This can increase the amount of fiber per unit length of the upper yarn layer, resulting in better water retention and less penetration of water into the inner layers of the brake hose.

Problems solved by technology

In such environments, moisture from the atmosphere can sometimes penetrate through the outer tube rubber layer 110 into the interior layers and become dissolved in the brake fluid, causing vapor locks and compromising the pedal feel.

Both of these conventional techniques result in better, although still not satisfactory, resistance to water penetration, and not only odes the latter technique require double-layer extruders, but the control of the thickness of the inner tube rubber layer is complicated.

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